A new family with a case of severe early-onset muscle fatigue and a peculiar maternally inherited painful swelling in chewing muscles associated with homoplasmic m.15992A>T mutation in mitochondrial tRNA.

A 16-year-old boy was evaluated for a history of exercise-induced fatigability associated with nausea even after minimal effort, lower limbs muscle hypotrophy, and swelling of the masseter muscles after chewing. Laboratory tests were remarkable for hyperlactatemia and metabolic acidosis after short physical activity. The muscle biopsy showed non-specific mitochondrial alterations and an increase in intrafibral lipids.

Structural rather than catalytic role for mitochondrial respiratory chain supercomplexes.

Mammalian mitochondrial respiratory chain (MRC) complexes are able to associate into quaternary structures named supercomplexes (SCs), which normally coexist with non-bound individual complexes. The functional significance of SCs has not been fully clarified and the debate has been centered on whether or not they confer catalytic advantages compared with the non-bound individual complexes. Mitochondrial respiratory chain organization does not seem to be conserved in all organisms.

Drosophila Mpv17 forms an ion channel and regulates energy metabolism.

Mutations in are a major contributor to mitochondrial DNA (mtDNA) depletion syndromes, a group of inherited genetic conditions due to mtDNA instability. To investigate the role of MPV17 in mtDNA maintenance, we generated and characterized a KO model showing that the absence of dMpv17 caused profound mtDNA depletion in the fat body but not in other tissues, increased glycolytic flux and reduced lifespan in starvation. Accordingly, the expression of key genes of glycogenolysis and glycolysis was upregulated in KO flies.

PPAR-gamma agonist pioglitazone recovers mitochondrial quality control in fibroblasts from -deficient patients.

Biallelic variants in are associated with a slowly progressive syndrome characterized by intellectual disability, spinocerebellar ataxia, cognitive decline and psychosis. The pitrilysin metallopeptidase 1 (PITRM1) is a mitochondrial matrix enzyme, which digests diverse oligopeptides, including the mitochondrial targeting sequences (MTS) that are cleaved from proteins imported across the inner mitochondrial membrane by the mitochondrial processing peptidase (MPP). Mitochondrial peptidases also play a role in the maturation of Frataxin, the protein affected in Friedreich's ataxia.